218 Dr. Schunck on Rubian and its Products of Decomposition, 



characteristic mark of distinction between them and rubianic 

 acid. Rubihydran is not precipitated from its aqueous solution 

 by any reagent except basic acetate of lead, which produces a 

 light brownish-red precipitate, which is paler and less bright 

 than the precipitates produced by the same reagent in solutions 

 of rubian or rubidehydran. The liquid filtered from this pre- 

 cipitate has still a light yellow colour, and ammonia produces 

 in it a fresh precipitate of a pale pink colour, after which it 

 appears colourless. Rubihydran is soluble in alcohol, but not 

 very easily. From the manner in which it is prepared it may 

 be inferred, that it is incapable of yielding rubianic acid by the 

 influence of the same agents which lead to the formation of the 

 latter from rubian. In order to obtain this substance in a per- 

 fectly dry state, it is necessary to heat it in the water-bath con- 

 tinuously for a day or two. In two analyses I obtained numbers 

 corresponding respectively with the formulae C^' H'*^ 0"*^ and 

 (^56 JJ42 Qs» \ Qjjjy succeeded once in obtaining it of the same 

 composition, or as free from water as when in combination with 

 oxide of lead. On this occasion it gave the following results : — 

 0'3940 grm. gave 0*7440 carbonic acid and 0"2130 water, 

 numbers which lead to the following composition : — 



On being burnt this specimen left no ash. 



The lead compound was prepared by dissolving the substance 

 in alcohol and then adding acetate of lead and ammonia, taking 

 care to leave an excess of rubihydran in solution, filtering, wash- 

 ing the precipitate with alcohol and drying, at first in vacuo, 

 and then for several hours in the water-bath. 



I. 0'8740 grm. of this compound gave 0*6720 carbonic acid 

 and 0-1970 water. 



0-7270 grm. gave 0-5850 sulphate of lead. 



II. 0-8860 grm. gave 0-6820 carbonic acid and 0-1930 water. 

 0-8465 grm. gave 0-6805 sulphate of lead. 



In 100 parts:— 



I. II. 



Carbon 20-96 20-99 



Hydrogen .... 2-50 2*42 



Oxygen 1734 17-44 



Oxide of lead . . . 59-20 5915 



100-00 100-00 

 The amount of oxide of lead here stands in no simple relation 



